Organic thin films continue to be heavily investigated for application in a variety of fields including organic light emitting devices (OLEDs), photovoltaic devices and organic photodetectors. Materials used to construct organic optoelectronic devices are relatively inexpensive in comparison to their inorganic counterparts, thereby providing cost advantages over optoelectronic devices manufactured with inorganic materials. Moreover, organic materials provide desirable physical properties, such as mechanical flexibility, permitting device constructions not attainable with rigid crystalline materials.
Organic thin films, however, suffer from performance disadvantages in comparison to crystalline inorganic materials. For example, some organic photovoltaic devices demonstrate efficiencies of 1% or less. Low efficiencies often displayed in organic photovoltaic devices result from a severe scale mismatch between exciton diffusion length (LD) and organic layer thickness. Efficient absorption of visible electromagnetic radiation generally requires organic film thickness of 500 nm or more. This thickness greatly exceeds exciton diffusion length which is typically about 50 nm, often resulting in exciton recombination. Given the disparity in performance, organic photovoltaic devices have encountered significant difficulty in challenging traditional inorganic devices.